Synopsis Figure 1. C-GCHG slinging at Cabot Island Ce rapport est galement disponible en franais. 1.0 Factual Information 1.1 History of the Flight The Canadian Coast Guard (CCG) Bell 212 helicopter (CTG 305) was re-supplying the lighthouse keeper's residence on Cabot Island with fresh water by means of three sets of four 40-gallon barrels slung in a net 120 feet under the aircraft. During each mission, four full barrels were lifted from a staging area at Newtown and flown six nautical miles (nm) east to Cabot Island, where the netload was detached from the bottom of the lanyard by ground crew. A similar load of empty barrels was reattached to the lanyard hook and slung back to Newtown, where they were exchanged for a load of four full barrels and replenished. One complete cycle required about 15 minutes to complete. On the day of the occurrence, the pilot commenced slinging operations at 1000 Newfoundland daylight time (NDT).1 He had completed 21 deliveries, stopping to refuel at a local refuelling facility at 1140, 1420, and 1635. During the last stop, the pilot ate a light meal before recommencing operations at about 1650. At about 1700, CTG 305 departed the staging area with a slung load of four full water barrels. During the trip to Cabot Island, the pilot radioed the ground crew, advising them to prepare items for the completion of the day's flying. The pilot then passed a message to St. John's Coast Guard Radio at 1702 that operations were proceeding normally. This was the last radio transmission from CTG 305. The helicopter arrived in the hover over Cabot Island at about 1705. Ground personnel exchanged the netload of full barrels for a similar netload of nearly empty barrels for the return flight. The aircraft then departed the island into wind on a northerly heading. Shortly after the aircraft's departure, a worker on the island noticed a splash. Small pieces of aircraft wreckage and the netload of barrels were observed floating a short distance from the shore, and rescue efforts were initiated. The pilot, who was the sole occupant, was fatally injured in the crash. The aircraft was destroyed, and approximately 200 litres of the aircraft's fuel and oil were released into Bonavista Bay. 1.2 Personnel Information The pilot was 39years old and held a valid commercial helicopter licence. His medical expiry date was 01 May 2001. The pilot had a total of 5012 flying hours, with 236hours on type. In the last 90days, he had flown 82hours, with 31hours on type. He had been on duty for 9hours before the occurrence. 1.3 Aircraft Information The CCG helicopter was based in St. John's and was maintained and flown by Transport Canada personnel. A review of the aircraft documentation indicated that the aircraft was maintained in accordance with existing regulations and approved procedures. All modifications, mandatory Airworthiness Directives, and required maintenance had been completed. The aircraft had flown 57.6hours since the completion of the last scheduled major overhaul on 15April 2000. Aircraft records after the maintenance overhaul did not indicate any outstanding or recurring maintenance items. The aircraft's weight and centre of gravity were within the prescribed limits. The helicopter was not equipped with a flight data recorder or a cockpit voice recorder, nor was either required by regulation. It was not equipped with an underwater locator beacon, nor was it required. The helicopter was equipped with emergency floatation devices, commonly referred to as pop-out floats. Pop-out floats can be inflated before ditching, and are meant to increase the survivability of a ditching by delaying the time at which a helicopter will begin to sink. 1.4 Meteorological Information There is no formal weather observation system in place at Cabot Island. However, the sky was clear, the wind was northerly at about 30 knots, and the outside air temperature was about two degrees Celsius. Water temperature records were reviewed by the Bedford Institute of Oceanography: the water surface temperature was found to be between one-half and one degree Celsius. 1.5 Communications The pilot was in direct radio communication with ground personnel at the staging area and at Cabot Island. The pilot also had radio contact with St. John's Coast Guard Radio. There were no communications from the pilot after departure from the island on the final leg. 1.6 Wreckage and Impact Information 1.6.1 Wreckage Location 1.6.2 Wreckage Examination Major components recovered from the ocean floor included the following: the aircraft cabin, both engines, the detached main rotor, the main transmission and surrounding structure, the tail boom, the detached tail rotor, and the 42- and 90-degree tail-rotor-drive gearboxes. There was massive deformation to the aircraft structure due to water impact. As well, there was damage from in-flight rotor strikes and salt water corrosion. Rotor strike marks indicated that the main rotor had detached from the helicopter before water impact. Main-rotor strikes were evident on the right side of the main fuselage and the tail boom. The tail boom had been struck twice by the main rotor, near the front at the baggage compartment, and aft of the 42-degree tail-rotor gearbox. There was crushing damage from water impact on the left side of the main fuselage and at the top of the tail boom, indicating that the tail boom separated from the fuselage before impact. The aircraft's various components were examined to the degree possible; no indication of a pre-existing mechanical malfunction was found. Damage patterns indicated that all the cabin and cockpit doors were closed at impact. The aircraft cargo release switch was found in the armed position. It is likely that this switch was armed throughout the mission to allow the pilot to immediately jettison the load. The main rotor was found in the southwest portion of the debris field. The tail rotor was recovered with other tail-rotor drive components in the middle portion of the debris field, just south of the fuselage cabin. An examination of the tail rotor revealed that the tail-rotor drive had separated in flight as a result of overload forces generated during the break-up sequence. The failure sequence of the tail-rotor components could not be determined. Damage patterns showed that the lower portion of the slinging hook assembly and the hook retaining ring had been torn rearward from the aircraft. These components were not found. The absence of crushing damage to components adjacent to the lower hook assembly indicates that the lower hook assembly was not on the aircraft at water impact. Impact marks show that the upper hook assembly was displaced 30 degrees to the rear at water impact. The slung load and the lifting equipment were recovered in good condition, with no indication that the equipment had contacted the helicopter. The plastic water barrels were inside the lifting net: three of the barrels were undamaged, the top of the fourth barrel had broken off. A discolouration was noted inside a crazed portion of the shattered windscreen. Witnesses had reported bird activity in the area, and a bird strike was considered as a possible source for the discolouration. This portion of the windscreen was analyzed in an attempt to determine if a bird had struck the windscreen; however, lab analysis could not determine the source of the discolouration. 1.7 Survival Aspects The pilot was found inside the aircraft. Because of the severe impact forces, the accident was not survivable. The pilot's lap belt had been only loosely attached, and the shoulder strap portion of the pilot's safety belt was not attached to the lap belt. The pilot was not wearing a life jacket or a helicopter passenger transportation (immersion) suit. A life raft was stowed in the cabin; however, it was not readily accessible to the pilot because a floor-to-ceiling cargo net was installed across the cabin, separating the cockpit from the cabin. The pop-out floats were not inflated, before or after the impact, and were recovered inside their protective cases which had been partially opened by impact forces. 1.7.1 Use of Shoulder Harness The accident pilot routinely wore the available shoulder harness; however, the range of body motion required during the vertical-reference operation likely precluded shoulder harness use. Normally, the pilot occupies the right pilot's seat; however, to clearly see the long line and the load, the pilot occupies the left seat during vertical-reference missions and leans markedly to the left. The approved shoulder harness does not allow the pilot to adopt this body position. It is a widespread practice for pilots not to use the shoulder straps during vertical-reference flights and to loosen the seatbelt portion to allow for increased range of motion. This helicopter had been configured and was approved for left-seat vertical-reference operations. During the high hover, the helicopter is inside the avoid area of the helicopter's height/velocity curve. Operations in the avoid area are risky because a successful autorotation is unlikely. Canadian Aviation Regulations (CARs) 605.24(5)(b) and 605.27(3) require that a helicopter used for external load operations be equipped with a seat and a safety belt that includes a shoulder harness for each person on board the aircraft. At least one pilot must be seated at the flight controls with the safety belt fastened during flight time. The TSB is aware of seven other helicopter accidents since 1985 in which available shoulder harnesses were not worn during long-line operations2. While it is unknown if the shoulder harnesses would have lessened injuries in these instances, studies have shown that approximately 70percent of all serious and fatal injuries in helicopter accidents occur primarily to the head, spine, torso, and neck. An analysis of helicopter crash dynamics by Coltman3 showed that, of the personnel who experienced a helicopter crash, only 9percent of those who were wearing a shoulder harness had severe injuries, compared with 34.3percent of those who wore only a lap belt. 1.7.2 Cold Water Survival A person suddenly immersed into cold water (less than 15degrees Celsius) faces four significant survival hurdles: cold shock, swimming failure, hypothermia, and post-rescue collapse. The first three are immediate hazards: cold shock can kill an unprotected person within 5minutes, swimming failure can be fatal in 15minutes, and fatalities from hypothermia can occur in 30minutes. An immersion suit and a life jacket provide immediate protection from these hazards, and a life raft provides longer-term protection by allowing survivors to remove themselves from the water. Neither the pilot nor the others transported over water that day wore immersion suits or were otherwise equipped to survive a ditching into the frigid water. Immersion suits were not required by regulation. Because the pilot sustained fatal injuries at impact, his degree of protection for water survival was not a factor. 1.7.3 Survival Equipment - Flights Over Water Subsections (4) and (5) of CAR 602.63 outline the regulatory requirements for the carriage of a life raft in helicopters: (4) No person shall operate over water a single-engined helicopter, or a multi-engined helicopter that is unable to maintain flight with any engine failed, at more than 25nauticalmiles, or the distance that can be covered in 15minutes of flight at the cruising speed filed in the flight plan or flight itinerary, whichever distance is the lesser, from a suitable emergency landing site unless life rafts are carried on board and are sufficient in total rated capacity to accommodate all of the persons on board. (5) No person shall operate over water a multi-engined helicopter that is able to maintain flight with any engine failed at more than 50nautical miles, or the distance that can be covered in 30minutes of flight at the cruising speed filed in the flight plan or flight itinerary, whichever distance is the lesser, from a suitable emergency landing site unless life rafts are carried on board and are sufficient in total rated capacity to accommodate all of the persons on board. The Transport Canada Operations Manual for CCG Helicopters applies the more stringent single-engine requirements to all its helicopters. In practice, however, a life raft is considered to be standard equipment on all flights. The operations manual also requires that one life preserver be on board and worn by each person when operating over water. In this occurrence, the pilot had a life preserver on board. However, he did not wear it, possibly because it interfered with his ability to position himself in the cockpit during vertical-reference operations. CAR 602.63 also sets the requirement for immersion suits: Where a helicopter is required to carry life rafts pursuant to subsection (4) or (5), no person shall operate the helicopter over water having a temperature of less than 10C unless: (a) a helicopter passenger transportation suit system is provided for the use of each person on board; and, (b) the pilot-in-command directs each person on board to wear the helicopter passenger transportation suit system. The operations manual states that, for multi-engine helicopters, wearing of immersion suits is mandatory when flying over water at distances greater than 15 nautical miles from ship, shore, or continuous ice capable of supporting the helicopter. 1.8 Tests and Research A representative flight was undertaken using another Bell 212 under similar conditions of wind and weight. It confirmed that the pilot's workload during the hover at the slinging area would have been quite high. The flight also showed that the pilot could have completed a climbing turn to an estimated en route altitude of 500 feet within the distance between the island and the accident site. 1.9 Additional Information 1.9.1 Accidents Related to Load Dragging Sixteen Canadian helicopter slinging accidents where the load dragged or the lifting equipment became snagged were reviewed. A major effect noted in these occurrences was a sudden and extreme change in aircraft attitude. If the drag was directly to the rear, a sudden nose-down attitude resulted. Proximity to the ground leaves little time for a pilot to react. If the drag is sufficient, internal hook components may be displaced from the normal range of travel and may disrupt other components. 1.9.2 Mast Bumping The Bell 212 has a teetering semi-rigid rotor system. The blades are free to flap vertically to compensate for various in-flight aerodynamic forces. On teetering semi-rigid rotor systems, the flapping angle is restrained to specific limits: on the Bell 212, a static stop on the blade yoke limits flapping by contacting the surface of the rotor mast. Exceeding the flapping limit in flight produces yoke-to-mast contact, commonly known as mast bumping. Fully developed mast bumping is usually catastrophic because the mast separates at crush points, which occur when the yoke static stops strike the mast violently. In forward flight, excessive flapping may result from inappropriate pilot response to low-G manoeuvres, the failure or loss of flight controls or rotor components, or external forces acting on the aircraft.